(1) Field of the Invention
The present invention is concerned with N-sulfo alkane amino alkane phosphonic acids and their alkali metal salts as well as with a process of producing such phosphonic acids and their salts, with a method of using said compounds, and with useful compositions comprising the same.
(2) Description of the Prior Art
N-Carboxy alkyl amino alkane diphosphonic acids and N-carboxy methyl amino aryl alkane diphosphonic acids are described in German Pat. No. 2,318,416.
British Pat. No. 1,142,294 discloses carboxy amino alkane phosphonic acids which are characterized by the group &gt;N--CH.sub.2 PO.sub.3 H.sub.2. Said compounds are obtained, for instance, by reacting amino acetic acid with formaldehyde and phosphorus trichloride in the presence of water.
The N-carboxy alkyl amino alkane diphosphonic acids disclosed in German Pat. No. 2,318,416 are produced by reacting amino alkane di- or, respectively, triphosphonic acids in an alkaline medium with formaldehyde and an alkali metal cyanide at a specific molecular proportion while heating.